Chlorite bleaching of wax and oil esters



Patented 2, i947 .onnoiu'ruimmounvozi a cams OF WAX AND OIL Ernest Stoscel and Ernest Zerner, New York, N. Y.,

alsignors to The Mathi'ecori Alkali W orks, Inc.,

New York, N. Y., a corporation of Virginia The process is especially adapted for the a bleaching of beeswax and by its use it is possible to obtain a product of satisfactory lightness of color without considerable cost and without destroying the valuable properties of the beeswax.

Beeswax bleached by this new process is very similar to sunbleached beeswax; furthermore, this new process can be very well combined with sunbleaching, thereby considerably reducing the time needed for bleaching such waxes by the action of the sun alone.

Thus, it is an object of the present invention to provide a new method of bleaching ester type waxes and oils, particularly for bleaching beeswax, which process is simple and inexpensive and adapted to reduce the time needed for sunbleaching substantially.

It is a further object of the present invention to produce chemically bleached beeswax having substantially the same properties as sun-bleached beeswax.

It is still another object of this invention to provide a chemical bleaching process which is well adapted to be combined with sun-bleaching I of beeswax.

With the above objects in view, the present invention mainly consists in bleaching ester type waxes and oils with chlorine dioxide, for instance by intimately mixing the wax in molten condition with one or more substances adapted to create, during this mixing, chlorine dioxide. This can be accomplished by adding sodium chlorite to the wax or oil to be bleached and stirring said mixture until the desired bleaching efiect is obtained; the chlorine dioxide necessary for bleaching can also be produced by mixing the wax or oil to be bleached in molten state with a small amount of a salt of chloric acid, e. g., sodium or potassium chlorate, and an organic polybasic acid, e. g., oxalic acid, and stirring this mixture. The salt of chloric acid reacts with the organic polybasic acid, forming chlorine dioxide which has a bleaching eiIect on the treated wax or oil.

The new process can be carried out in various ways. Preferred embodiments of the same will be described below in detail:

1., Crude dark-colored beeswax is melted after having been previously clarified in known way. To this molten wax, a small amount of an aqueous sodium chlorite solution is added and this solution intimately mixed with the molten wax by stirring for about 20 to 30 minutes, until the desired bleaching effect is obtained. It should be noted that this mixing period should be as short as possible, as otherwise the wax takes on a brownish color.

After the desired bleaching eflect has been ob- No 1mm. Application September a, 1942.

, Serial No. 457.119

'2 Claims. (01. zoo-'42:)

tained, it is advisable to wash the bleached wax thoroughly with steam by blowing the same into the molten wax. It is also advisable to treat the thus partly cleaned wax with an acid, preferably phosphoric or oxalic acid, destroying thereby theemulsion formed during the bleaching Process by reaction of the sodium chlorite with the free acids of the wax. Although addition of this phosphoric acid has the advantage of destroying the emulsion formed during bleaching, it sometimes causes darkening of the bleached wax through development of chlorine. In order to avoid this effect, it is herewith proposed to add, before the acid treatment, a very small amount or sodium thiosulphate which binds the chlorine developed during the acid treatment, thereby preventing darkening of the wax.

After the above described acid treatment, the bleached wax is left to settle and washed again with steam and a sodium thiosulphate solution until all traces of chlorine and chlorine dioxide are removed. Thereafter, the thus treated wax may be exposed to the action of the sun and further bleached, if desired.

It is possible to obtain white wax by the above treatment alone; but'there is always the danger that the bleached wax acquires a, brownish color due to excess addition of bleaching chemicals. Therefore, it is often preferable to bleach the wax by the above described chemical process only partly and to expose the thus semi-bleached wax to the action of the sun. This combined chemical and sun bleaching has proved especially advantageous.

Although the proportions of the ingredients used for the above described new bleaching process may be varied to a considerable extent, certain relations have been found to be particularly advantageous. Thus, if a thousand parts of beeswax have to be bleached, it is preferable to add for bleaching to the molten, purified crude wax from about four to eight parts of sodium chlorite dissolved in about eight to twenty-four parts of warm water. The wax bleached by this solution is thereafter treated with about one part of sodium thiosulphate and then mixed with about five parts of phosphoric acid diluted in water. The amount of steam used for cleaning depends only on the cleaning effect required, 1. e., as much steam must be used as necessary to remove entirely from the wax all chlorine and chlorine dioxide traces.

2. The chlorine dioxide needed for bleaching purposes can not only be formed by adding of sodium chlorite as described above, but also by intimately, mixing the beeswax in molten state with a small amount of a salt ofa chloric acid and an organic polybasic acid. As salts for this purpose may be added chlorates of alkali metals and alkaline earth metals, preferably sodium 3. chlorate or potassium chlorate; as organic polybasic acids may be used, tor instance oxalic acid, citric acid, tartaric acid, malelc acid, lumaric acid and aconitic acid.

This process is preferably carried out by melting the crude beeswax alter preliminary clean ing, heating it to a temperature not exceeding Thus it is often possible even to omit addition of water entirely as the water present in the mixture is suflicient to create the necessary reaction, namely to form the chlorine dioxide needed for the bleaching process. Also this process can be combined with consecutive sunbleaching oi the wax.

While we have illustrated and described the invention as embodied in processes for the bleachwing of ester type waxes and oils, especially of beeswax, we do not intend to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of our invention.

What we claim as new and desire to secure by Letters Patent is:

1. The process of bleaching ester-type wax comprising the steps of melting said wax; adding to said molten wax a small amount of an aqueous sodium chlorite solution thus obtaining an unacidified wax-sodium chlorite mixture; stirring said unacidified wax-sodium chlorite mixture until said wax is bleached to the desired extent; and treating the thus bleached wax with an acid, thereby destroying the emulsion formed during bleaching.

2. The process of bleaching ester-type oil comprising the steps of adding to said oil a small amount of an aqueous sodium chlorite solution thus obtaining an unacidified oil-sodium chlorite mixture; stirring said unacidifled oil-sodium chlorite mixture until said oil is bleached to the desired extent; washing the thus bleached oil with steam; and mixing said bleached and washed oil with phosphoric acid, thereby destroying the emulsion formed during bleaching.

3. In the process of bleaching beeswax, the steps of heating one thousand parts of said wax until the same is molten; adding to said molten wax about four to eight parts of sodium chlorite dissolved in about eight to twenty-four parts of water thus obtaining an unacidified wax-sodium chlorite mixture; stirring said unacidified waxs'odium chlorite mixture until the wax is bleached to the desired extent; washing the thus bleached wax with steam; intimately mixing said bleached and washed wax with about five parts of phosphoric acid; and finally washing it again with steam until all traces of sodium chlorite and chlorine dioxide formed during bleaching are removed.

4. The process of bleaching ester-type wax, comprising the steps of melting said wax; adding to said molten wax a small amount of an aqueous sodium chlorite solution thus obtaining an unacidified wax-sodium chlorite mixture; stirring said unacldlfied wax-sodium chlorite mixture until said wax is bleached to the desired extent; washing the thus bleached wax with steam; adding a small amount of sodium thiosulphate, thereby destroying any sodium chlorite not consumed during said bleaching and said washing with steam; and after said bleaching destroying the emulsion formed during said bleaching by means or an acid.

5. The process of bleaching ester-type oil, comprising the steps of adding to said oil a small amount oi. an aqueous sodium chlorite solution thus forming 'an unacidifled oil-sodium chlorite mixture stirring said unacidifled oil-sodium chlorite mixture until said oil is bleached to the desired extent; washing the thus bleached oil with steam; adding a small amount of sodium thiosulphate thereby destroying the sodium chlorite traces not consumed during said bleaching and said washing with steam; and mixing the thus obtained bleached and washed oil with phosphoric acid, thereby destroying the emulsion formed during bleaching.

6. In the process of bleaching beeswax, the steps of heating one thousand parts of said wax until the same is molten; adding to said molten wax about four to eight parts of sodium chlorite dissolved -in about eight to twenty-four parts of water thus obtaining an unacidified wax-sodium chlorite mixture; stirring said unacidified waxsodium chlorite mixture until the wax is bleached to the desired extent; washing the thus bleached wax with steam; adding about one part of sodium thiosulphate thereby destroying substantially all the sodium chlorite not consumed during said bleaching and said washing; intimately mixing the thus bleached and washed molten wax with about five parts of phosphoric acid; and finally washing it again with steam until all traces of sodium chlorite are removed.

7. The process of bleaching a substance selected from the group consisting of ester-type waxes and ester-type oils comprising the steps of melting said substance; adding to said molten substance a small amount of an aqueous sodium chlorite solution so as to obtain an unacidified mixture of said substance and said sodium chlorite and to bleach said substance to the desired extent; and treating the thus bleached substance with an acid, thereby destroying the emulsion formed during bleaching,

Y ERNEST STOSSEL. ERNEST ZERNER.

REFERENCES CITED;

The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 389,898 Perrine Sept. 25, 1888 1,580,136 Hamburger Apr. 13, 1926 2,113,433 Reichert Apr. 5, 1938 2,194,956 Taylor Mar. 26, 1940 2,269,667 Kaufiman Jan. 13, 1942 2,383,629 Treacey Aug. 28, 1945 OTHER REFERENCES Taylor, Sodium Chlorite, Ind. Eng. Chem., July 1940, page 899. (Copy in scientific library.)

Photostat in 8-1085. 

